With the recent proliferation of computer and communication networks, there is a growing interest in leveraging existing network resources to provide end users with network connectivity on a demand basis. Thus, as an end user's demand for network resources grows or shrinks, the user may choose to add or remove network capacity by procuring connectivity from other entities. These other entities, generally referred to as operators, operate and maintain physical network resources. Other business entities referred to generally as service providers serve as intermediaries between end users and the operators, further simplifying the procurement of network resources for the end user. Management of the network requires coordination between these different entities.
FIG. 1 illustrates a conceptual network configuration 100 in which communications between two local area networks (LANs) 106, 112 is accomplished using a service provider network 118. Such a configuration is useful for interconnecting and extending LANs 106, 112, which typically cover a limited geographic region, such as a home or office. With the service provider network 118, the different LANs 106, 112 may reside on different floors of the same building, within different building of the same campus, or in different cities, states or even countries. One such example of extended LAN operations use a technique referred to as a virtual LAN (VLAN). Thus, Ethernet frames generated by the first user 102 can be forwarded through the first LAN 106 across an interconnecting network 118 and to a second user 114 on the second LAN 112. From the end user's perspective, they appear to be operating on the same LAN. Beneficiaries of such interconnected LANs include business entities, such as large corporations, whose operations span different geographical regions.
The service provider network 118 uses transport technology to relay local traffic, such as Ethernet frames between LANs 106, 112. Transport technologies such as Optical Transport Network (OTN) and Synchronous Digital Hierarchy (SDH) have been developed to provide generic and all-purpose transport containers for moving both voice and data across the network. In order to establish and maintain the underlying network connectivity, such transport technologies typically provide a separate channel for distributed signaling communications and other distributed communications in relation to provisioning, managing and monitoring network resources.
For example, the communications channel can be used for order-wire or voice communications between maintenance entities to coordinate testing and other maintenance activities, such as software downloads. For configurations in which multiple entities are involved in providing end-to-end network connectivity, each entity would benefit from such a communications channel to provision and maintain related network resources under their control. Preferably, communications on such a data communications channel are confined to the managing entity. Thus, each of the different entities may have a respective data communications channel that is isolated from the other entities. Such isolation would be valuable to business operations in which proprietary information may be shared. Leakage of such information to other entities would be undesirable.
With recent interest in deploying Ethernet as a transport technology, a similar capability would be beneficial. However, having evolved in enterprise environments, Ethernet is missing this capability as there was no such need for a separate maintenance channel. Others have proposed using a dedicated virtual local area network (VLAN) for the purpose of an Ethernet data communications channel. When different entities are involved in providing end-to-end network connectivity, they share the same forwarding plane. Separate VLANS would be required for each data communications channel needed by Operators and Service Providers. Moreover, dedicating the VLANs still does not prevent unwanted leakage of information.